What are plant hormones? Name the plant hormones responsible for the following: (i) Growth of stem (ii) Promotion of cell division (iii) Inhibition of growth (iv) Elongation of cells
What are plant hormones? Name the plant hormones responsible for the following: (i) Growth of stem (ii) Promotion of cell division (iii) Inhibition of growth (iv) Elongation of cells
Official answer
Plant hormones (or phytohormones) are chemical substances produced naturally in plants, in extremely low concentrations, which regulate physiological processes such as growth, development, and responses to the environment.
The plant hormones responsible for the given functions are:
(i) Growth of stem: Gibberellins
(ii) Promotion of cell division: Cytokinins
(iii) Inhibition of growth: Abscisic acid
(iv) Elongation of cells: Auxins
Marking scheme
- 1.Definition of plant hormones: 1 Mark
- 2.Naming the hormone for growth of stem (Gibberellins): 0.5 Mark
- 3.Naming the hormone for promotion of cell division (Cytokinins): 0.5 Mark
- 4.Naming the hormone for inhibition of growth (Abscisic acid): 0.5 Mark
- 5.Naming the hormone for elongation of cells (Auxins): 0.5 Mark
Hint
Think of the four major classes of phytohormones: Auxins, Gibberellins, Cytokinins, and Abscisic Acid, and match them to their primary physiological roles.
Quick oral answer
Plant hormones are chemical substances that control and coordinate growth and development in plants. Examples include Auxins (cell elongation), Gibberellins (stem growth), Cytokinins (cell division), and Abscisic Acid (growth inhibition).
Common mistakes
- 1.Confusing the roles of auxins and gibberellins, as both are involved in growth.
- 2.Spelling 'Abscisic acid' incorrectly as 'Abscisic acid' or confusing it with ethylene.
- 3.Forgetting that cytokinins are specifically concentrated in areas of rapid cell division.
Analysis and explanation
Plant hormones are chemical messengers that coordinate various activities in plants. Unlike animals, plants do not have a nervous system, so they rely entirely on chemical coordination.
- Auxins are synthesized at the shoot tips and help cells grow longer (cell elongation).
- Gibberellins help in the growth of the stem by promoting internodal elongation.
- Cytokinins promote rapid cell division, especially in areas of rapid cell division like fruits and seeds.
- Abscisic acid is a growth inhibitor that reverses the effects of growth-promoting hormones, causing wilting of leaves and dormancy of seeds.
Interesting facts
The term 'phytohormone' was coined by Thimann in 1948.
Abscisic acid is also known as the 'stress hormone' because it helps plants cope with adverse environmental conditions like drought by closing stomata.
Question details
Q11 of 37 questions
- Board
- CBSE
- Class
- Class 10
- Subject
- Science
- Year
- 2019
- Section
- Section C
- Marks
- 3
- Type
- Short Answer
- Chapter
- Control and Coordination
- Topic
- Plant Hormones
- Bloom's level
- Remembering
- Syllabus topic
- Coordination in Plants
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Frequently asked questions
How many marks does this question carry in CBSE Class 10 Science 2019?
This question carries 3 marks in the CBSE Class 10 Science 2019 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Control and Coordination" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Plant Hormones" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2019 paper?
This is a Short Answer question from Section C in the CBSE Class 10 Science 2019 paper.